Drivers’ memo #10: Seasonal changes in travel efficiency

Woohoo … we cracked a ton! We now have 101 members in the test driver panel and received over 70 monthly data sets last month. We are on track for public launch next month.

Continuous improvement: Hopefully you will have enjoyed the new reports on your dashboard – lots more will appear in the next month, including much better estimates of the financial benefits of LEVs – the prototype equations were crude and deliberately set low while we waited for the funding to develop the software. Data input has been streamlined and customised for each LEV model, and the clumsy registration process that you endured is now halved in length and simplified.

Safeguarding our scientific credentials: A description of Flip the Fleet’s rationale and design is now posted at www.flipthefleet.org/resources, alongside another report on how we estimate the volume of fuel you avoid by driving an LEV. Several of you provided superbly thorough peer review of these reports to help safeguard the scientific reliability of our reports – thanks for access to your collective brains and knowledge. The design rationale (Flip the Fleet Report #1) acknowledges all of the test drivers that helped up until the beginning of April.

Are you ready for winter? The preliminary data from the test drivers already hints at the seasonal pulse in travel efficiency. Again, please don’t forget that the sample size is small and not yet fully distributed around New Zealand, and we need to watch for a couple of years to confirm the seasonality. However our sneak peek below suggests a fall in efficiency from around 7.0 to 6.4 km/kWh between summer and winter – that’s about a 9% drop in range.

The winter drop is probably partly due to your running heaters, lights and wipers, and partly due to increased drag of wet roads. But the graph is also a minimum estimate of the seasonal contraction in range because a cold battery holds less energy than a warm one – irrespective of the efficiency with which you convert this to pushing your car down the road, in winter there will be less energy to use even at the start of your journey. If we can grow the Flip the Fleet membership we will be able to compare the seasonal swings between models of cars, and in southern regions compared to the balmy north.

May’s 1-click survey: We asked you whether “#LeadingTheCharge reached a lot of potential purchasers of EVs that would have been hard to reach by other means”. Your consensus was that it successfully reached prospective EV buyers, but some of you warned that we are going to have to get inventive to build the media coverage in such an event in future. See the full results in the separate post in this discussion page. We owe all the #LeadingtTheCharge drivers a beer or a wine next time we meet them!